Colonoscopy is the current standard method for evaluation of colonic disorders such as colorectal cancer, IBD, polyps, and other conditions.

Colonic cancers are a major concern in the Middle East and the world in general, and every institute has attempted to initiate various clinical and investigatory procedures to detect the disease early in its development. From 2005 till 2010 an audit conducted at the Royal Liverpool University revealed that out of 8910 colonoscopies, 693 were incomplete (7.8%), and for 25% of failure was because of inadequate bowel preparation.

An adequate bowel preparation regimen is not only effective in cleansing the colon but should be well tolerated by patients. The polyethylene glycol (PEG) solution, an isosmotic non-absorbable polymer, is generally used for bowel preparation, because of its safety, effectiveness, and good tolerability. Quality of bowel cleansing depends not only on the formula used, but the preparation regimen also plays a role. Split dosing of the laxative offers, in general, better cleansing than a single dose preparation.

A large survey was also done in the USA in 2018 and demonstrated that split dose treatment was more tolerable than single-dose treatment for bowel preparation.

Also more recent study shows split-dose bowel preparation for colonoscopy with PEG is better than single-dose, in terms of adequate bowel preparation and polyp detection.

On the other hand , a large randomized trial of PEG regimens show, low-volume same-day resulted in similar bowel cleanliness compared with high-volume or low-volume split-dosing. Willingness to repeat and tolerability were superior with low-volume same-day compared with high-volume split-dose and similar to low-volume split-dose. Another most recent one demonstrated that same-day morning PEG regimen can be considered an effective well-tolerated, and acceptable bowel preparation for colonoscopy.

A same-day dose of bowel cleanser has several benefits compared with split-dose or previous-day dose: the fasting time is shorter and there is no sleep disturbance, which can be associated with split-dose or previous-day regimen.

Inclusion Criteria:

- All patients undergoing elective colonoscopy

Exclusion Criteria:

• Presence of sever renal impairment. (Creatinine clearance < 30 ml/min or patient on hemodialysis).
• Sever congestive heart failure (NHYA III or IV).
• Pregnant woman.
• History of bowel obstruction or resection.
• Known allergies to polyethylene glycol.
• Refusal of consent for the study.
• Signs of liver cell failure as ascites and hepatic encephalopathy.
• Electrolytes disturbances